The present invention relates to the selective distribution of cable television ("CATV") signals or the like to subscribers, and more particularly to a method and apparatus for remotely supplying or denying subscriber access to cable services such as television programs, movies, and special events.
In cable television networks, subscribers are connected with the aid of signal distribution devices to a transmission line carrying television programs, radio programs, and associated data.
A disadvantage with conventional cable television systems is that only subscribers who indicate that they want to receive cable television services are connected to the distribution system. Installation of new subscribers requires a technician to travel to the subscriber's residence to connect the cable. Upon a termination of service, a technician has to travel again to the residence to disconnect the subscriber from the distribution network.
Certain programs transmitted over the cable television network are premium programs that the subscriber must pay an additional fee to receive. In the past, subscribers have been authorized to receive such programs in various ways. In some systems, a technician must travel to the subscriber's residence to install or remove traps (i.e., signal filters) or descramblers in the subscriber drop. In other systems, addressable converter/descramblers are provided to the subscribers. A cable system operator can authorize or deauthorize the receipt of programs by transmitting control signals to each subscriber's addressable descrambler. Although this technique has been very successful, the converter/descramblers that must be provided to each subscriber are somewhat expensive.
The converter/descramblers used in prior art systems include tuners to enable the subscriber to select a channel to be viewed. Certain program specific "tag data" is transmitted on the sound carrier of the program signal as AM data. This requires a separate AM data receiver to be provided in the converter/descrambler to receive the channel tagging data. An example of such a prior art system can be found in the Impulse 7000 Series Addressable Converters available from the Jerrold Division of General Instrument Corporation, Hatboro, Pennsylvania.
In some cable television systems, a multiple system operator ("MSO") provides signals to a number of different local cable system operators ("CSO"). The CSO's each serve subscribers in a different geographic area, and typically provide their subscribers with different subsets of the full set of services available from the MSO. Often, a single service provided by an MSO will be found on different channels in each of the local systems. Thus, for example, the "Home Box Office" movie service may be provided on channel 2 by one CSO and on channel 8 by another CSO. An MSO who desires to keep track of the various services provided to different subscribers on different channels, e.g., for accounting and/or authorization purposes, has a complicated task. The process becomes more complicated in a system that offers dynamic events, such as pay-per-view programs. In such systems, an MSO or CSO must keep track of which subscribers have ordered what events, when the events are to be broadcast, the channels on which the events are to be broadcast, and the authorization protocols that will enable authorized subscribers to receive the programs.
It would be advantageous to provide a relatively inexpensive signal distribution device that could be remotely controlled from a cable television headend to enable or disable the reception of particular cable television channels by individual subscribers. It would be particularly advantageous to provide such a distribution device that does not require a tuner to tune to specific channels, and yet permits an MSO to control access to programming regardless of the difference in physical channel assignments and specific distribution wiring used by individual CSO's and provided to individual subscribers. It would be further advantageous to provide such apparatus with a limited number of signal ports or "access devices" for distribution of premium programs to individual subscribers, without thereby limiting the number of premium services offered by the MSO system wide.
It would also be advantageous to provide a signal distribution device that can be economically installed at each residence in a neighborhood during the original installation of a cable television system. Such a device should enable a cable system operator to selectively couple and decouple a plurality of signal traps or other access devices in series with a subscriber drop to enable and disable the reception of designated program channels, without allowing subscribers or others to switch the access devices themselves.
It would be further advantageous to provide the distribution device with a remotely controlled on/off position, wherein cable television signals carried on the transmission line can be blocked from entering residences of those who are not subscribers. Such an on/off position would enable a cable operator to remotely disconnect terminated subscribers, and connect new subscribers.
The present invention relates to distribution apparatus and a signal distribution method having the abovementioned and other advantages. More specifically, a novel "logical channel" construct is disclosed wherein access devices on a subscriber distribution device are assigned logical channel numbers. The access devices are switched to provide or deny subscriber access to particular services based on service codes associated with the logical channels and service code authorization data. The service code to logical channel associations and the authorization data may be downloaded to the distribution device from a headend, and may be altered by a system operator periodically or on a real-time basis as services and subscriptions change.